Pneumatic trim device



Feb. 24, 1970 -M. N. WEBER PNEUMATIC TRIM DEVICE 4 Sheets-Sheet 1 FiledMay 16, 1968 INVENTOR. fit/20:2 Z l Veer TURN E KS Feb. 24, 1970 M. N.WEBER 3,496,899

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Filed May is, 1968 INVENTOR. 275212022 27. Weer BY M M. N. WEBERrummmmic TRIM DEVICE Feb. 24, 1970 Filed May 16 1968 4 Sheets-Sheet 4 TTO/QNEYS United States Patent 3,496,899 PNEUMATIC TRIM DEVICE Milton N.Weber, 20655 Audette,

Dearborn, Mich. 48124 Filed May 16, 1968, Ser. No. 729,612 Int. Cl. B63b1/18, 1/32 US. Cl. 11466.5 20 Claims ABSTRACT OF THE DISCLOSURE Thepresent invention relates to trim devices for boats and, moreparticularly, to a trim tab actuated by fluid pressure.

A well known problem encountered when operating a power boat with themeans for propulsion at the rear, is a change in attitude of the boat aspower is increased. This change in attitude more specifically involves araising of the bow out of the water and a lowering of the stern into thewater. This high bow attitude increases the profile drag, for examplethe depth to which the boat extends into the water. This increased draghas an adverse effect on the fuel usage as well as tending to slow theboat down for a given power setting. It is, therefore, desirable toprovide means on a boat for correcting the tendency of the boat to ridestern low in the water and bring the boat into a condition where it willplane. When a boat planes, the pointed portion of the bow is knifingthrough the water, and the boat has a maximum amount of free board, thatis, more of the sides of the hull of the boat ride out of the water thanin the water. Under these conditions the least amount of the hullsurface is in contact with the Water thereby minimizing the drag andincreasing the boats performance.

The prior art shows many devices for bringing a boat into a condition ofplane, but there are various disadvantages associated with each. Forexample, the prior art shows planing surfaces or trim tabs that can bepositioned downwardly of the hull of a boat at an angle with respectthereto to cause the bull to lift out of the water to bring about thedesired planing condition. One common form of this type of trim plane isa mechanically set unit that is adjusted before a boat is underway andis pre-set at an angle which it is expected will be most efficient inbringing the boat into plane when operated. Of course, the exactoperating conditions of a boat are difficult to predict and, in fact,will change as the boat is underway, for example due to fuelconsumption. For this reason the setting of these mechanical devices isa compromise between the boat having a given weight distribution and anexpected weight distribution, while also being restricted to making theboat plane only under a given speed condition. When any of thesepredicted values change, the planing devices are ineffective and, infact, can become detrimental to the performance of the boat. Therefore,such devices have not found wide usage.

Another form of trim device found in the prior art involves adeflectable trim plane that is actuated by mechanical means such as by ajackscrew. The jackscrew can be either manually operated, or in someinstallations is power driven, as by an electric motor. In this manner,

3,496,899 Patented Feb. 24, 1970 "ice the aforementioned shortcoming ofthe fixed mechanical device is overcome in that the angle of the planingsurface can be adjusted while the boat is underway thereby compensatingfor changes in operating conditions. These devices have shortcomings inthat, during installation, there must be multiple holes made in the hullof the boat which are subject to leakage in order to bring the deviceinto engagement with the trim tab. In addition, there is a great deal ofinvolved apparatus which necessarily increases the expense, and thesecomplex mechanical controls are subject to malfunction and corrosion. Afurther complication of a mechanically operated remote control trim tabis that if the trim tab is struck by an obstacle in the water, damagenecessarily results due to the nonresilient nature thereof. This type ofdevice has come into wider usage than the aforementioned fixed device,but is yet limited only to the more expensive boats wherein the greatexpense of a remote control mechanically operated trim tab can bejustified. Therefore, most boats constructed today are not provided withthis type of trim tab.

Still another kind of trim tab found in the prior art is the type wherean attempt is made to provide a fluid operated trim tab that provides aneasy mode for remote control and which provides a resilient surface sothat if a foreign object in the water is struck by the tab, very littledamage ensues. However, there are certain disadvantages associated withthe pneumatically operated trim tab shown in the prior art. For example,a fluid operated trim tab can very readily deflect a planing surfaceinto the path of water passing the boats hull, but means normally mustbe provided for the return of the trim tab to a position of rest whenthe trim is to be changed to a lower setting or when trim is to bedispensed with. Therefore, springs or some other type device areconnected to the end of the tab to provide this return action, and thisreturn device necessarily involves another item subject to corrosion andmalfunction. In addition, when the fluid operating device takes the formof a cylinder, there is great expense involved and again theinstallation is rather complex to carry out. In addition, a cylinder hasmetallic parts which are subjected to the corrosive elements associatedwith a boats environment, and a serious maintenance problem existsrelative thereto. For this reason, a cylinder type fluid device foroperating trim tabs has not found wide usage on boats. 7

When the type of fluid operated trim tabs found in the prior art whichinvolve inflatable bags are used, another problem presents itself. Theinflatable bags shown in the art are resilient members that, whenexpanded, tend to assume a round shape. This is the natural tendency ofan inner tube type of resilient bag. The prior art does not show meansfor restraining the inflation of certain areas of these bags so thatthey will assume a desired shape which is compatible with a deflectabletrim tab. In addition, the fluid operated trim tabs of the prior art aremainly adapted for mounting on the transom of a boat because of theirthickness which would dictate, if they were mounted on the bottom of thehull of the boat, that they would provide suflicient drag under certainoperating conditions to offset the advantages that they would provideunder other more favorable operating conditions. If recesses in the hullof the boat are provided for such devices, as shown in the prior art toaccommodate their thickness, an add-on version of the trim tab isprecluded and the trim tab can be installed on a boat only as originalequipment. This seriously limits the market for such devices.

Fluid operated trim tabs of the prior art that use inflatable bags areeither unrestrained and, therefore, tend to ballon or present too muchvolume for expansion initially so that the response of the device israther slow.

In addition, if a hand pump or bulb were used, the volume of airrequired to inflate the bag would be excessive and, therefore, timeconsuming.

The present invention contemplates the solution to the aforementionedproblems by providing a device for craft of the type which moves througha fluid comprising trim means adapted for attachment to the craft andincluding a planing member having first and second extremities with thefirst extremity pivotal about a position adjacent the second extremity.An inflatable means is provided which coacts with the planing member forpivoting the planing member while being inflated, the inflatable meanshaving an increasing available volume in a direction toward the secondextremity from a position adjacent the first extremity. Preferably theinflatable means is inelastic and, when inflated defines cross sectionalareas in successive parallel planes transverse to the direction of thesecond extremity and increases in cross section going toward thatdirection. In this manner, a bag made of some inelastic material can layapproximately fiat between a planing member and hull of a boat and is ofgenerally triangular shape in an uninflated condition. The bag generallydefines an elongated isosceles triangle with the base of the trianglebeing attached between the trim plate and the hull. The tip of theisosceles triangle shaped bag extends along the length of the trim platewhich is of an inherently resilient material. Therefore, when inflationof the bag commences, the tip of the trim plate offers the leastresistance to inflation so the tip of the bag inflates first deflectingthe tip of the trim plane away from its position of rest. As more air ispumped into the bag, the bag progressively fills from the tip toward thebase of the isosceles triangle shaped portion. The bag being inelastic,when the bag fills to its inflated shape, a wedging action is generatedgoing toward the connection of the trim plate to the hull and causesfurther deflection of the plate. As this occurs, the volume of the bagincreases so that there is greater bearing surface acting against theplate so that practically every bit of inflation is translated intodeflection of the plate. Due to the relatively small volume of the bag,the movement of the trim plate in a deflecting manner is very quick. Itshould also be noted that as the bag is inflated, starting at the angleopposite the base of the isosceles triangle, inflated portion of the bagdraws out of engagement with the trim plate and the hull of the boat,and only the uninflated portion, or partially inflated portion,continues in engagement with the hull or trim plate. Therefore, the bagessentially retains its triangularity in a plane essentially parallel tothe boats hull and assumes a triangularity in a plane perpendicularthereto.

The bag and planing member can be secured beneath a boarding stepprojecting to the rear of the transom of the boat if desired. The entireassembly is sufliciently thin so that the bag and planing member can bedisposed in a depression in the boats hull or mounted on the hullssurface as desired. The bag is generally composed of a nylon reinforcedplastic material of sheet form with the sheet being folded and heatfused into an enclosurure. In one embodiment the bag is inflated by ahand bulb located near an operating station. In another embodiment, thebag is inflated by a vacuum driven pump regulated by a control at anoperating station.

In another embodiment, the bag has a rigidifying member disposed insideto insure a desired inflated bag configuration, and the bag is securedto the hull of the boat on a line substantially along the length of thebag and on a line along the Width thereof at an end. The bag isinflatable by fluid pressure to form a planing surface for the boat thatis angularly disposed with respect to the boats hull with the surface ofthe bag being the actual planing surface. In this embodiment, the bagreturns to a position adjacent the boats hull when pressure is relievedtherein by the natural resilience of the bags material. This bag is alsoadaptable to be carried on an extension from the boats transom such asunder a boarding step. 1

Accordingly, it is an object of the present invention to provide animproved trim device for a boat that includes a planing member pivotalabout a first extremity and deflectable away from a boats hull by theinflatable means coacting with the planing member for pivoting theplaningmember, the inflatable means having an increasing availablevolume for expansion in a direction going from the free end of theplaning member to the first extremity.

It is another object of the present invention to provide an improvedtrim device, as set forth in the previous object, wherein the inflatablemeans is inelastic.

It is still another object of the present invention to provide animproved trim device for a boat wherein a deflectable trim plane isextended by inflating a bag that is generally the shape of an isoscelestriangle and is secured to the boat along the base portion of thetriangular shape so that when inflated, the bag essentially retains itstriangularity in a plane parallel to the boats hull and assumes atriangularity in a plane perpendicular thereto.

It is yet a further object of the present invention to provide animproved trim device as set forth in the previous objects wherein theinflatable means, when inflated, dcfines cross sectional areas insuccessive parallel planes transverse to a line running from the freeend of the planing members toward the first extremity.

It is a further object of the present invention to provide an improvedtrim device for a boat wherein a deflectable plane is moved by a baghaving a fluid pressure generated therein by a hand bulb located near anoperating station.

It is yet a further object of the presnet invention to provide animproved trim device for a boat wherein a bag is attached to the hull ofthe boat and has a rigidifying member disposed inside which restrainsthe bag against free inflation and forms an aerodynamic shaped enclosurebeneath the hull of the boat that acts as a trim plane.

Other objects and intended advantages of the present invention will bereadily appreciated as the same becomes better understood by referenceto the following detailed description when considered in connection withthe accompanying drawings wherein:

FIGURE 1 is an elevational view of a boat with parts broken away showingthe subject invention in its operative environment.

FIGURE 2 is an elevational view of the transom of a boat with thesubject trim plane shown in a deflected condition.

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2.

FIGURE 4 is a diagrammatic illustration of a poweroperated trim planearrangement in accordance with the present invention.

FIGURE 5 is a sectional view similar to the view in FIGURE 3 but withthe trim plane in deflected condition.

FIGURE 6 is a perspective view with parts broken away of the inflatablebag of the subject invention.

FIGURE 7 is a diagrammatic illustration of a manual fluid pressureproducing means for the subject invention.

FIGURE 8 is a view, partly in section, taken along line 8-8 of FIGURE 7.

FIGURE 9 is a sectional view taken along line 99 of FIGURE 10.

FIGURE 10 is a sectional view of another embodiment of the presentinvention shown in a position of rest.

FIGURE 11 is a sectional view of the embodiment of FIGURE 10 with thetrim plane shown in deflected condition.

FIGURE 12 is a sectional view of another modification of the presentinvention shown mounted under a boarding step suspended from the transomof a boat.

FIGURE 13 is another modification of the present invention shownattached to the transom of the boat but mounted beneath the hullthereof.

Referring to FIGURE 1, a boat generally designated by numeral isillustrated with trim tabs 12 shown mounted on hull 14 thereof in adeflected condition brought about by inflation of bag 16. Air line 18supplies fluid under pressure that is regulated by valve assembly 20mounted near the operating station of the boat 10.

FIGURE 2 is an enlarged view of the boat of FIG- URE 1 showing trim tabs12 in a deflected position as viewed from behind the transom of boat 10.

Referring to FIGURE 3, one means of mounting the trim tabs on the boatis shown wherein the whole assembly is contained within recess 22 formedin hull 14. It is understood that a surface mounting on the hull is alsodesirable due to the thinness of the device. Trim tab 12 is composed ofa resilient material, such as stainless steel and is substantially acontinuation of hull 14 so as to provide a relatively smooth outersurface for the hull in the area where the trim tab is located. Trim tabor planing member 12 is shown as a relatively flat rectangular member,but it is understood that the size, shape or thickness of the tab 12 canbe suited to a particular operative environment. In addition, it mightbe desirable when mounting the tab on a severely contoured area of ahull to have the tab contoured in a complementary manner so that a cleanprofile is provided for the hull or so that an aerodynamic shape isgenerated for specific desired conditions of lift. Recess 22 issufliciently deep so that when the planing surface of trim tab 12 isoperably mounted, bag 16 is compressed between trim tab 12 and the baseof recess 22. An aperture is provided through the hull for the receptionof tubular element 24 which is bonded in any well known manner to bag16. The free end of tab 12 is termed a first extremity, and screws 26pass through trim tab 12 and bag 16 prior to being threaded into thebody of hull 14 near a second extremity of tab 12.

Referring to FIGURE 5, bag 16 is shown in expanded disposition withresilient trim tab 12 shown in a deflected condition. It is noted inFIGURE 5 that bag 16 has a substantially triangular shape up to point 26in a perpendicular manner with respect to hull 14. The flat plate areaof trim tab 12 up to point 26 is sufiicient to cause the lift to hull 14that is desired. The outer portion, or extension, of trim tab 12extending beyond point 26 is free to deflect and can easily be deflectedtoward hull 14 if a foreign object is struck by the tab as the boat ismoving through the water. If the impact is sufliciently great, bag 16will be distorted against hull 14 thereby further cushioning the shockto trim tab 12. When pressure is relieved in bag 16, resilient trim tabwill move back to the position as shown in FIGURE 3 due to its owninherent resilience.

Referring to FIGURE 6, the bag 16 is shown as being generally the shapeof an isosceles triangle and having holes 30 passing therethrough,adapting the reception of screws 26. The tip is adjacent the firstextremity of the tab 12, and the base of the triangle is adjacent thesecond extremity of tab 12. This is the base portion of the triangularshape so that when inflated the bag will essentially retain itstriangularity in a plane parallel to the boats hull and, as seen inFIGURE 6 and in FIGURE 5 will assume a triangularity in a shapeperpendicular to the boats hull. The bag 16, when inflated, definescrosssectional areas that increase in size when measured from the firstextremity of tab 12 toward the second extremity thereby near its anchorpoint. When a point near element 24 is reached, continuing toward theanchor point, the cross-sectional areas diminish. Therefore, the bag isconstrained between tab 12 and the boats hull. The tab 12 is resilient,and it is noted that it takes less force at the free end to deflect tab12 than at any other point nearer its anchor point. Near this end thebag is pointed and has the least volume. Therefore, when inflationstarts, the tip, being less constrained than other portions of the bag,fully inflates first with the bag progressively filling toward itslargest cross-sectional area or volume. In other words, the inflatedcross-sectional area in successive parallel planes going from the tip ofthe isosceles triangle shape toward the base increases as the bag isfilled up to a certain point and then decreases as the second extremityof tab 12 is approached by a completely inflated volume of the bag. Thebag is inelastic and as a part fills, it becomes free of the hull andtab 12, and all further air input goes toward bringing about furtherdeflection of tab 12 and filling of the unfilled volume in bag 16. Inthis manner, the bag provides the amount of support to the trim tab 12in the area of deflection to maintain a set angularity when in aninflated condition. The bag is composed of a reinforced plastic materialthat is originally in sheet form and then is folded as at 32 and heatfused into an enclosure. Element 24 is likewise fused onto bag 16 in anywell known manner, such as by electric welding. Bonding is alsoacceptable in certain installations.

Referring to FIGURE 7, valve assembly 20 is shown, and has a pressureinput through fitting 32. In the embodiment of FIGURE 7, fitting 32communicates pressure from bulb 34 which is more clearly shown in FIG-URE 8.

Referring to FIGURE 8, a check valve assembly 36 is illustrated so thatwhen pressure is generated by squeezing bulb 34, an increase of pressureis registered in manifold 38, and this pressure is trapped therein.Manifold 38 communicates with a pair of trim tab arrangements throughlines 40 and 42 respectively. Valve assembly 20 is of a commonconstruction that allows lines 40 and 42 to be separately controlled byknobs 44 and 46 respectively. Dump buttons 48 and 50 are disposed in thecenter of knobs 44 and 46 respectively so that it is possible toseparately regulate the pressure in the pair of trim devices so that animbalance therein can be created to offset a load shift in the boat.

Referring to FIGURE 4, a very similar arrangement is shown wherein avacuum pump 52 is substituted for the bulb assembly 34 and is of thetype that is operated through line 54 communicating with a vacuum sourcesuch as the intake manifold of an internal combustion engine. Outlet 56of pump 52 communicates with fitting 32 in much the same manner as bulb34. Pump 52 is a well known type such as the pumps manufactured by theHadley Manufacturing Company of Toledo, Ohio, and is utilized as an airpressure control for load level ing mechanisms of station wagons. Pump52 will pressurized line 58 and manifold 38 with air pressureselectively routed to lines 40 and 42 as desired. Valvr: assembly 20 isso designed that a selective pressure dump can be effected throughdumping ports not shown, or pump 52 can be controlled through a solenoidoperated valve assembly likewise not shown. The manner of controllingpump 52 is not considered to be a portion of the present invention andcan be affected in any way suitable in a particular installation asdetermined by Y the designer of the system.

Referring to FIGURE 10, another embodiment of the subject invention isillustrated in which a reaction member 60 is carried within bag 16, withbag 16 being bonded to the base of recess 22, preferably up as far aspoint 62, as seen in FIGURE 11. Bag 16 in this environment is of aplastic material having a slight amount of elasticity, which elasticityprovides the return means for the planing member herein shown whenpressure is relieved from bag 16. It is noted that reaction member 60 isa rigidifying member and tends to control the lateral shape of bag 16when inflated. Bag 16 can take any shape therefore in this embodiment inview of the fact that its outer dimension is controlled, and it isprevented from going into a generally circular bag when inflated. Asseen in FIGURE ll, the generally triangular vertical shape is alsomaintained up to approximately point 64 which is equivalent to point 28as shown in the embodiment of FIGURE 5. Therefore, the same effectiveplaning area is presented to the water passing hull 14 as in theprevious embodiment with the same resistance to shock from striking asubmerged object that is available in the embodiment of FIGURE 5. FIGURE11 has the added advantage of presenting an aerodynamic shape so thatthe water flow thereby is considerably smoother than in the planingmembers shown in the prior art. It should also be pointed out that boththe embodiment of FIGURE and embodiment of FIGURE 11 provides the devicewith an adjustability heretofore unknown. That is, when a planing memberis deflected a given amount to bring about a performance desired at agiven speed, and the speed is increased without changing the planingmember, the force of the water rushing against the planing member willtend to depress it thereby automatically regulating the trim a limitedamount which can be an important feature when slight variations in speedare undertaken which are insuflicient to warrant the changing of thetrim. It should also be noted that, whereas in both the embodiments ofFIG- URE 5 and FIGURE 11 the trim arrangements are shown as mounted inrecess 22, they are sufficiently thin in cross section, when retracted,to be mounted on the outside of the hull of the boat so as to adapt thesubject device to be available as an after-market installation if theywere not originally installed in the boat when sold.

Also available for after-market installation is the embodiment of FIGURE12. The same device shown in FIGURE 5 is illustrated in this embodimentwhich is mounted under boarding step 66. This, of course, is a much.easier mode of installation that, in the case of small boats, can bereadily made when the boat is pulled from the water. The embodiment ofFIGURE 13 is very similar in that the boarding step concept is alsoused, but bracket 68 can be bolted to the transom 70 of boat withoutmoving the boat from the water, yet allowing the trim plane device to besituated on the base of hull 14. Both the embodiments of FIGURES 12 or13 are particularly adaptable for use on small boats such as those usedfor water skiing.

The various embodiments shown in the subject device tend to illustratemore clearly the versatility of the device in that it can be used fororiginal equipment manufacture or can be used in the after-market foradd-on to an existing boat. In addition, the device is adapted to bemultiply mounted, that is in pairs or groups larger than pairs on eitherside of a boat of a greater length than is practical to control withonly the pair mounted as shown in FIGURE 2. To explain further, a boatin cess of 30 feet, for example, might req-uirethe flat plate area thatis presented by a pair of trim tabs on either side of the hull. Inaddition, due to the location of the propellers on certain boats, thatis dual engine boats, it may be important to locate a trim tab on eitherside of the water flow into the propellers to prevent cavitation. Instill other installations, depending upon the weight distribution withinthe boat, it might be appropriate to mount trim tabs further toward thebow of he boat than shown in the illustrations in the drawings. Ofcourse, the exact position of the mounting of the trim tabs is left tothe particular artisan involved in the installation, for all boats havedifferent weight distributions and are oriented toward operation atdifferent speeds which might change the most desirable point on the hullof the boat for locating the trim tabs.

Another feature extending the utility of subject devices is that themounting of the trim tabs of the subject invention involves only makingone hole in the hull of the boat that must be sealed. This is the holethrough which element 24 extends. The remaining part of the installationis made very simply by screws into the hull of the boat, whether thetrim tab arrangement is situated in a recess, such as shown at 22, or onthe surface of the hull which would be the normal installation pointwhen added on to the boat after construction thereof.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology that has been used is intended to bein the nature of Words of description rather than of limitation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventioncan be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A device for a craft of the type which moves through a fluidcomprising: trim means adapted for attachment to the craft and includinga planing member having first and second extremities with the firstextremity pivotal about a position adjacent the second extremity; andinflatable means coacting with said planing member for pivoting saidplaning member while being inflated; said inflatable means having anincreasing available volume in a direction toward said second extremityfrom a position adjacent said first extremity.

2. A device as set forth in claim 1 wherein said inflatable means isinelastic.

3. A device as set forth in claim 2 wherein said inflatable means, wheninflated, defines cross-sectional areas in successive parallel planestransverse to said direc tion which increase in said direction.

4. A device as set forth in claim 3 wherein said cross sectional areasin said successive planes increase to a maximum and thereafter decreasein said direction to said second extremity.

5. A device as set forth in claim 4 wherein said inflatable meanscomprises a bag which when inflated and viewed in side elevationdiverges from a position adjacent said first extremity toward saidsecond extremity and then converges the remainder of the distance to aposition adjacent said second extremity.

6. A device as set forth in claim 5 wherein said bag has a generallytriangular configuration when viewed in plane with opposite divergingsides and a base, said base being disposed adjacent said secondextremity.

7. A device as set forth in claim 6 wherein said bag is disposedadjacent said planing member whereby the bag may react between theplaning member and the craft.

8. A device as set forth in claim 7 wherein said planing member isyieldable and has memory.

9. A device as set forth in claim 8 wherein said planing member comprisespring steel.

10. A device as set forth in claim 9 wherein said plane member isrectangular.

11. A device as set forth in claim 8 including fluid pressure means incommunication with said bag for inflating said bag.

12. A device as set forth in claim 5 wherein said planing member isdisposed within said bag.

13. A device as set forth in claim 12 wherein said planing member isrectangular.

14. A device as set forth in claim 12 including fluid pressure means incommunication with said bag for inflating said bag.

15. A device as set forth in claim 8 wherein said bag comprises areinforced plastic material.

16. A device for a craft of the type which moves through a fluidcomprising: trim means adapted for attachment to the craft and includinga planing member having first and second extremities with the firstextremity pivotal about a position adjacent the second extremity, andinflatable means adapted to react between said planing member and thecraft and adapted to contact the craft along the length thereof whendeflated and for successively moving out of contact with the crafttherealong only in a direction from said first extremity toward saidsecond extremity as said inflatable means is inflated.

17. A device as set forth in claim 16 wherein said inflatable means isinelastic.

18. A device for a craft of the type which moves through a fluidcomprising: trim means adapted for attachment to the craft and includinga planing member having first and second extremities with the firstextremity pivotal about a position adjacent the second extremity, andinelastic inflatable means adapted to react between said planing memberand the craft and adapted to contact the craft along the length thereofwhen deflated and for successively moving out of contact with the crafttherealong in a direction from said first extremity toward said secondextremity as said inflatable means is inflated, said inflatable means,When inflated, defining crosssectional areas in successive parallelplanes transverse to said direction which increase in said direction.

19. A device as set forth in claim 18 wherein said cross sectional areasin said successive planes increase to a maximum and thereafter decreasein said direction to said second extremity.

20. A device as set forth in claim 19 wherein said inflatable meanscomprises a bag which when inflated and viewed in side elevation,diverges from a position adjacent said first extremity toward saidsecond extremity and then converges the remainder of the distance to aposition adjacent said second extremity.

References Cited UNITED STATES PATENTS 3,313,262 4/1967 Yunker et a1.11466.5

ANDREW H. FARRELL, Primary Examiner

